All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Plastic pollution is a global environmental crisis for many reasons. Plastics are made to be durable rather than degradable. The ones that are biodegradable demonstrate shortcomings such as high production costs and functionality problems, which result in their challenges to be produced or used on a large scale. Furthermore, the existence of a large variety of plastic polymer types has led to an increase in public confusion on the subject of what is recyclable. Plastic consumerism is inevitable and continues to grow. Not only is existing plastic pollution prevalent and ubiquitous, but new plastic waste is generated at an alarming rate. This global excess of plastic waste harms the environment and pollutes the food chain.
A common component of the municipal waste stream and marine debris is contaminated plastics or contaminated plastic waste. Current methods that exist for the treatment of contaminated plastics or contaminated plastic waste include pyrolysis, incineration, landfill disposal, and mechanical recycling after thorough cleaning. Plastic pyrolysis is energy intensive and produces low-grade fuels that require expensive refinery steps to be useful chemicals. This cannot be economically accomplished. Plastic incineration requires massive amounts of upfront capital to establish, needs substantial power and maintenance, and also results in adverse environmental consequences, as does the disposal of plastics in landfills. These expensive methods pollute the environment and do not utilize the contaminated plastic waste materials that could be used as a raw feedstock for new products. Almost all post-consumer and post-industrial contaminated plastic waste are centralized to material recovery facilities, where they can become further contaminated. Mechanical recycling is not economically viable because cleaning contaminated plastics or contaminated plastic waste requires intensive resources and labor.
Less than 15% of global plastics produced is recycled because the process is not economical. As much as 50% of recycling bin content in the United States is considered contamination and is normally discarded by the traditional recycling process. Even though plastics are the most abundant materials in the waste recovery stream, they are the least preferred material for recycling because most plastic, with the exception of water bottles and milk jugs, have few or no viable downstream markets. In 2014, the EPA has calculated the amount of plastic films not recycled was 3.6 million tons. Since then, packaging plastics have increased in volume at waste plants due to the wide adoption of food delivery and online shopping.
Although much research has been done on the bioremediation of plastic pollution, biological methods alone are expensive, inefficient, and difficult to scale. Such techniques, including those involving ex vivo cellular degradation or insect larval digestion, also have not coupled plastic waste treatment with the production of value-added economical products.
Thus, there is a need in the art for methods and systems that provide for the decomposition of contaminated plastic waste that overcome the limitations of known methods.